SyncMySubsWhat is SDH?
SDH stands for Subtitles for the Deaf and Hard of Hearing. It carries everything a regular subtitle track does, and then the parts of the soundtrack you would otherwise miss without hearing it: who is speaking, the sound effects, and the music. If you have ever seen a line like [door creaks] or MARIA: We need to go in a subtitle, that is SDH.
SDH versus regular subtitles
Regular subtitles are written for people who can hear the audio but need the words, most often as a translation. They carry the dialogue and little else, because the viewer can already hear the door slam and the music swell. SDH is written for people who cannot hear the audio at all, so it fills in what sound alone would tell you. In practice that means three additions on top of the dialogue:
- Speaker labels, so it is clear who is talking when the speaker is off screen or hard to place.
- Sound effects, written in brackets, such as [glass shatters] or [phone ringing].
- Music and lyrics, from a simple [ominous music] cue to the actual words of a song.
SDH versus closed captions
People often use the terms interchangeably, but they come from different places. Closed captions are the older broadcast standard, encoded into the video signal and traditionally shown as white text on a black bar. SDH delivers the same kind of information, the non-speech audio and speaker cues, but in an ordinary subtitle format that is styled like subtitles and works for streaming, discs, and digital delivery where broadcast captions are not available.
When you might want to remove it
SDH is exactly what you want for accessibility, and you should keep it when the point is to make content available to deaf and hard-of-hearing viewers. But if you can hear the audio and simply want clean dialogue on screen, or you are reusing an SDH file as the basis for a translation, the sound cues and speaker labels get in the way. The Remove SDH tool strips the bracketed cues and the speaker names and leaves just the spoken lines. For a step-by-step walkthrough, see the guide to removing SDH. Everything runs in your browser, and your file is never uploaded.
FAQ
What does SDH stand for?
Subtitles for the Deaf and Hard of Hearing. On top of the dialogue that a regular subtitle carries, SDH describes the non-speech audio, such as who is speaking, sound effects, and music, so a viewer who cannot hear the soundtrack still follows everything.
What is the difference between SDH and regular subtitles?
Regular subtitles assume you can hear the audio and usually just carry the spoken words. SDH assumes you cannot hear it, so it adds speaker labels, sound-effect descriptions, and music cues. That extra information is what makes SDH accessible, and also what you strip out with Remove SDH if you want a dialogue-only file.
What is the difference between SDH and closed captions?
Both convey the non-speech audio, but closed captions are the older broadcast standard, encoded in the video signal and often shown as white text on a black bar. SDH delivers the same kind of information in an ordinary subtitle format for streaming, discs, and digital delivery where traditional broadcast captions are not supported.
How do I remove SDH from a subtitle file?
Use the Remove SDH tool. It strips the bracketed sound and music cues and the speaker name labels, leaving just the spoken lines, and it runs entirely in your browser so the file is never uploaded. The Remove SDH guide walks through it step by step.